asp.net webservices: Hi I wrote the following webservice

[WebMethod]
public void test()
{
return ;
}

I added this in the web.config file:
<webServices>
<protocols>
<add name="HttpPost"/>
<add name="HttpGet"/>
</protocols>
</webServices>

but when I try to consume the service via httpGet I get this error:

System.IndexOutOfRangeException: Index was outside the bounds of the array.
at System.Web.Services.Protocols.HttpServerType..ctor(Type type)
at System.Web.Services.Protocols.HttpServerProtocol.Initialize()
at System.Web.Services.Protocols.ServerProtocolFactory.Create(Type type,
HttpContext context, HttpRequest request, HttpResponse response, Boolean&
abortProcessing)